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Change-Id: Icbf40b26a25c7084efd062a0a66385450ec537aa Reviewed-on: https://go-review.googlesource.com/16699 Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>
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// Copyright 2015 The Go Authors. All rights reserved. | ||
// Use of this source code is governed by a BSD-style | ||
// license that can be found in the LICENSE file. | ||
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// Transport code's client connection pooling. | ||
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package http2 | ||
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import ( | ||
"net/http" | ||
"sync" | ||
) | ||
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// ClientConnPool manages a pool of HTTP/2 client connections. | ||
type ClientConnPool interface { | ||
GetClientConn(req *http.Request, addr string) (*ClientConn, error) | ||
MarkDead(*ClientConn) | ||
} | ||
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type clientConnPool struct { | ||
t *Transport | ||
mu sync.Mutex // TODO: switch to RWMutex | ||
// TODO: add support for sharing conns based on cert names | ||
// (e.g. share conn for googleapis.com and appspot.com) | ||
conns map[string][]*ClientConn // key is host:port | ||
keys map[*ClientConn][]string | ||
} | ||
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func (p *clientConnPool) GetClientConn(req *http.Request, addr string) (*ClientConn, error) { | ||
return p.getClientConn(req, addr, true) | ||
} | ||
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func (p *clientConnPool) getClientConn(req *http.Request, addr string, dialOnMiss bool) (*ClientConn, error) { | ||
p.mu.Lock() | ||
for _, cc := range p.conns[addr] { | ||
if cc.CanTakeNewRequest() { | ||
p.mu.Unlock() | ||
return cc, nil | ||
} | ||
} | ||
p.mu.Unlock() | ||
if !dialOnMiss { | ||
return nil, ErrNoCachedConn | ||
} | ||
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// TODO(bradfitz): use a singleflight.Group to only lock once per 'key'. | ||
// Probably need to vendor it in as github.com/golang/sync/singleflight | ||
// though, since the net package already uses it? Also lines up with | ||
// sameer, bcmills, et al wanting to open source some sync stuff. | ||
cc, err := p.t.dialClientConn(addr) | ||
if err != nil { | ||
return nil, err | ||
} | ||
p.addConn(addr, cc) | ||
return cc, nil | ||
} | ||
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func (p *clientConnPool) addConn(key string, cc *ClientConn) { | ||
p.mu.Lock() | ||
defer p.mu.Unlock() | ||
if p.conns == nil { | ||
p.conns = make(map[string][]*ClientConn) | ||
} | ||
if p.keys == nil { | ||
p.keys = make(map[*ClientConn][]string) | ||
} | ||
p.conns[key] = append(p.conns[key], cc) | ||
p.keys[cc] = append(p.keys[cc], key) | ||
} | ||
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func (p *clientConnPool) MarkDead(cc *ClientConn) { | ||
p.mu.Lock() | ||
defer p.mu.Unlock() | ||
for _, key := range p.keys[cc] { | ||
vv, ok := p.conns[key] | ||
if !ok { | ||
continue | ||
} | ||
newList := filterOutClientConn(vv, cc) | ||
if len(newList) > 0 { | ||
p.conns[key] = newList | ||
} else { | ||
delete(p.conns, key) | ||
} | ||
} | ||
delete(p.keys, cc) | ||
} | ||
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func (p *clientConnPool) closeIdleConnections() { | ||
p.mu.Lock() | ||
defer p.mu.Unlock() | ||
// TODO: don't close a cc if it was just added to the pool | ||
// milliseconds ago and has never been used. There's currently | ||
// a small race window with the HTTP/1 Transport's integration | ||
// where it can add an idle conn just before using it, and | ||
// somebody else can concurrently call CloseIdleConns and | ||
// break some caller's RoundTrip. | ||
for _, vv := range p.conns { | ||
for _, cc := range vv { | ||
cc.closeIfIdle() | ||
} | ||
} | ||
} | ||
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func filterOutClientConn(in []*ClientConn, exclude *ClientConn) []*ClientConn { | ||
out := in[:0] | ||
for _, v := range in { | ||
if v != exclude { | ||
out = append(out, v) | ||
} | ||
} | ||
// If we filtered it out, zero out the last item to prevent | ||
// the GC from seeing it. | ||
if len(in) != len(out) { | ||
in[len(in)-1] = nil | ||
} | ||
return out | ||
} |
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